1. Field of the Invention
The present invention relates to fuel supply system of a vehicle and, more particularly to a fuel supply system of vehicle including a fuel tank disposed at a level not higher than that of a carburetor combined with an engine.
2. Description of the Related Art
In a fuel supply system including a fuel tank disposed at a level higher than that of a carburetor to supply the fuel by the pressure head of the fuel contained in the fuel tank, it is usual to attach the fuel outlet line to the bottom wall of the fuel tank. The fuel outlet line is provided with a fuel cut valve to prevent the fuel contained in the fuel tank from flowing into the carburetor while the engine is stopped.
In a fuel supply system disclosed in Patent document 1 (JP-A 2003-182672) including a fuel tank disposed at a level not higher than that of a carburetor combined with an engine, it is usual to pump up the fuel contained in the fuel tank and to supply the fuel through a fuel supply line to the carburetor by a fuel pump. Since the fuel does not flow naturally from the fuel tank into the carburetor while the vehicle is stationary and the engine is stopped, the fuel supply line of the fuel supply system is not provided with any fuel cut valve.
Even in the fuel supply system including the fuel tank disposed at a level not higher than that of the carburetor, it is possible that the fuel contained in the fuel tank flows into the carburetor if the vehicle is shaken during transportation on a vehicle carrier or if the pressure in the fuel tank rises greatly due to temperature change. If the fuel flows accidentally into the carburetor, the fuel evaporated in the carburetor makes it difficult for the engine to start or the fuel is wasted. The fuel pump of the fuel supply system disclosed in Patent document 1 is disposed apart from the fuel tank. Therefore, it takes a long time for the fuel pump to pump up the fuel from the fuel tank when the engine is started, particularly, when the engine is started for the first time after shipping or after a long interruption of operation and, consequently, it takes a long time to start the engine.